Synthesis of Elemane Bis-Lactones from Santonin – Synthesis of the Reported Structure ofseco-Isoerivanin Pseudo Acid and Formal Synthesis of (+)-8-Deoxyvernolepin

The synthesis of the reported structure for seco-isoerivanin pseudo acid (1) and of an elemane bis-lactone 5 from santonin (4) through a common vinylic precursor 12 is described. Compound 5 is a known intermediate in a previous synthesis of the antitumor compound (+)-8-deoxyvernolepin (3). The vinyl group of 12 underwent a regio- and diastereoselective anti addition of an external electrophile and an intramolecular condensation to yield either the selenolactone 13 or the hydroxylactone 17. The lactones 13 and 17 served as key intermediates in the total synthesis of 1 and 5 respectively. A revision of the structure of seco-isoerivanin pseudo acid to the C-10 epimer is suggested on the basis …

ChemInform Abstract: Synthesis of Sesquiterpenes via Silicon-Guided Rearrangement of Epoxydecalins

A survey of the rearrangement of methyldecalins via C-5 carbocation intermediates, with special attention to the silicon-guided rearrangement of epoxydecalins is provided. A TMS group properly posi...

Silicon guided rearrangement of epoxydecalines to spirocyclic compounds. Synthesis of gleenol and axenol from carvone

Abstract The synthesis of the spirocyclic sesquiterpenes (−)-gleenol and (−)-axenol in enantiomerically pure form has been achieved starting from R-(−)-carvone. The key step is the silicon guided acid-promoted rearrangement of a 9-trimethylsilyl-5,6-epoxy-noreudesmane prepared from 3-trimethylsilyldihydrocarvone in several steps involving Robinson annulation, enone deconjugation and epoxidation. Acid treatment of the epoxy-noreudesmane gave a norspiroaxane as the main product, which was used as intermediate for the synthesis of two naturally occurring sesquiterpenes gleenol and axenol.

Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-?-rotunol and All Diastereomers of 6,11-Spirovetivadiene.

The synthesis of the spirovetivane sesquiterpenes (+)-anhydro-beta-rotunol and all the diastereomers of 6,11-spirovetivadiene in enantiomerically pure form has been achieved starting from santonin. The key step is the silicon-guided acid-promoted rearrangement of a 1-trimethylsilyl-4,5-epoxyeudesmane prepared from santonin in several steps involving lactone reductive opening, conjugate addition of TMSLi-CuCN, deoxygenation of a carbonyl group, and epoxidation. Rearrangement of the epoxide gave a spiro[4,5]decanediol which was used as a synthetic intermediate. From this compound, (+)-anhydro-beta-rotunol was prepared after elimination of the primary hydroxyl group in the side chain, followed…

Stereoselective Synthesis of (+)-11βH,13-Dihydroestafiatin, (+)-11βH,13-Dihydroludartin, (−)-Compressanolide, and (−)-11βH,13-Dihydromicheliolide from Santonin

Starting from 2 and 3, obtained from santonin (1), we have synthesized natural guaianolides 4-7. Chemoselective epoxidation of 2 gave (+)-11betaH,13-dihydroestafiatin (4), and epoxidation of 3 followed by regioselective elimination of the hydroxyl group afforded (+)-11betaH,13-dihydroludartin (5). Sharpless' mild regioselective ring-opening of 4 and 5 followed by hydrogenolysis yielded (-)-compressanolide (6) and (-)-11betaH,13-dihydromicheliolide (7), respectively.

Highly Diastereoselective Arylation of (S)-Mandelic Acid Enolate: Enantioselective Synthesis of Substituted (R)-3-Hydroxy-3-phenyloxindoles and (R)-Benzylic Acids and Synthesis of Nitrobenzophenones.

An easy access to substituted (R)-3-hydroxy-3-phenyloxindoles, (R)-benzylic acids, and benzophenones is described. The reaction of the lithium enolate of the (2S,5S)-cis-1,3-dioxolan-4-one derived from optically active (S)-mandelic acid and pivalaldehyde with several o- and p-halonitrobenzenes proceeds readily to give the corresponding arylation products in good yields and diastereoselectivities. The reduction of the nitro group with Zn/HCl/EtOH in the o-nitro arylation products with concomitant intramolecular aminolysis of the dioxolanone moiety leads directly to enantiomerically pure (R)-3-hydroxy-3-phenyloxindoles. On the other hand the basic hydrolysis of the dioxolanone moiety in all t…

Total Syntheses of Four Stereoisomers of 4α-Hydroxy-1β,7β-peroxy- 10βH-guaia-5-ene

[reaction: see text]. The first total syntheses of four stereoisomers of 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene are reported starting from the readily available (+)-dihydrocarvone. These compounds have been synthesized from dienes (-)-isoguaiene and (-)-10-epi-isoguaiene by tandem ene hydroperoxylation-[4 + 2] cycloaddition with O(2) followed by selective reduction. The structure of the natural 4alpha-hydroxy-1beta,7beta-peroxy-10betaH-guaia-5-ene isolated from Liabum floribundum has been confirmed.

ChemInform Abstract: A Non-Catalyzed Ring-Opening Aminolysis Reaction of Sesquiterpene Lactones.

Abstract Santonin (1) and other sesquiterpene lactones (6–10) react cleanly with pyrrolidine at room temperature to afford γ-hydroxyalkylamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated alkylamides.

ChemInform Abstract: Synthetic Studies Toward Natural Furanosesquiterpenoids from Santonin. Synthesis of (+)-1,2-Dihydrotubipofuran.

Abstract Santonin (1) was converted into (+)-1,2-dihydrotubipofuran (13) via a synthetic pathway involving a very easy preparation of 7,11-ene-8,12-olide and 8,12-furan moieties and A-ring elaboration on the eudesmane framework.

ChemInform Abstract: The Reduction of α,β-Unsaturated Nitriles and α- Halonitriles with Sodium Hydrogen Telluride.

Abstract Sodium hydrogen telluride reacts chemoselectively with α,β-unsaturated nitriles and α-halonitriles linked to aromatic and aliphatic substituents to give the corresponding saturated nitriles with good yields.

Silicon-guided rearrangement of 10-methyl-4,5-epoxydecalins. Methyl versus methylene migration

The Lewis acid-promoted rearrangement of two 10-methyl-4,5-epoxydecalins bearing a trimethylsilyl (TMS) group on C-1 or C-9 has been studied. Migration of the C-9 methylene group to C-5 is the major reaction pathway when the TMS and the oxirane groups are on the same ring while methyl migration results exclusively when they are on different rings.

ChemInform Abstract: Stereoselective Synthesis of 7,11-Guaien-8,12-olides from Santonin. Synthesis of Podoandin and (+)-Zedolactone A.

Photochemical rearrangement of hydroxy ester 2, easily obtained from santonin (1), afforded butenolide 4, a good starting material for the synthesis of 7,11-guaien-8,12-olides. Compound 4 has been transformed into compound 10, which has been used for the synthesis of podoandin (5) and (+)-zedolactone A (ent-6). Regioselective elimination of the acetyl group on C10 afforded directly podoandin (5). For the synthesis of ent-6, a hydroxyl group has been regio- and stereoselectively introduced at the 4α-position through the 3α,4α-epoxide 15. The basic hydrolysis of the 10-acetyl group in compound 18 took place with concomitant intramolecular conjugated addition of the alkoxide to the butenolide …

Role of Seroalbumin in the Cytotoxicity of cis-Dichloro Pt(II) Complexes with (N^N)-Donor Ligands Bearing Functionalized Tails

Given the potent anticancer properties of cisdiamminedichloroplatinum( II) and knowing its mode of action, we synthesized four new cis-[PtCl2(N^N)] organoplatinum complexes, two with N-substituted pbi ligands (pbiR = 1-R-2-(2-pyridyl)benzimidazole) (namely, 1 and 2) and two more with 4,4′-disubstituted bpy ligands (bpy = 2,2′-bipyridine) (namely, 3 and 4). We explored their cytotoxicity and ability to bind to deoxyguanosine monophosphate (dGMP), DNA, and albumin models. By 1H NMR and UV−vis spectroscopies, circular dichroism, agarose gel electrophoresis, differential scanning calorimetry measurements, and density functional theory calculations, we verified that only 3 can form aquacomplex s…

Sesquiterpenes, flavonoids and lignans from Onopordon acaulon

Abstract From the methanol extract of Onopordon acaulon , four flavonoids, four lignans and three sesquiterpenes were isolated. Two eudesmane derivatives are described for the first time.

Ultrasound assisted reductive cleavage of eudesmane and guaiane γ-enonelactones. Synthesis of 1α,7α,10αH-guaian-4,11-dien-3-one and hydrocolorenone from santonin

Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.

Functionality transfer from C8 to C9 in sesquiterpenes. Synthesis of the named Herbolide E from artemisin.

Abstract The key intermediate 6 was obtained in five steps from artemisin (1). The spectroscopic characteristics of the synthetic product 7a reveal that the proposed structure for the natural herbolide E must be revised.

Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-β-rotunol and All Diastereomers of 6,11-Spirovetivadiene

The synthesis of the spirovetivane sesquiterpenes (+)-anhydro-beta-rotunol and all the diastereomers of 6,11-spirovetivadiene in enantiomerically pure form has been achieved starting from santonin. The key step is the silicon-guided acid-promoted rearrangement of a 1-trimethylsilyl-4,5-epoxyeudesmane prepared from santonin in several steps involving lactone reductive opening, conjugate addition of TMSLi-CuCN, deoxygenation of a carbonyl group, and epoxidation. Rearrangement of the epoxide gave a spiro[4,5]decanediol which was used as a synthetic intermediate. From this compound, (+)-anhydro-beta-rotunol was prepared after elimination of the primary hydroxyl group in the side chain, followed…

Computational study of the interaction of proflavine with d(ATATATATAT)2 and d(GCGCGCGCGC)2

Abstract The interaction of proflavine (PR) with two B-DNA decamers of alternating AT and GC sequence, called [deca(dG-dC)]2 and [deca(dA-dT)]2, respectively, was computationally investigated by the ONIOM method, exploiting a three-layer QM/QM/MM hybrid approach. The highest level QM method was applied to the model system, which comprises the intercalation site (5th and 6th base pairs) and the inserted PR molecule. The connecting sugar phosphate backbone was added in the medium layer region. Both higher and medium level layers, differing in the size of the basis set used, were treated by the DFT MPWB1K functional. The full system in the lower layer was described by the empirical AMBER force…

ChemInform Abstract: Synthesis of Elemane Bis-lactones Structurally Related to Vernolepin.

Abstract The chemical transformation of santonin into an elemane bis -lactone structurally related to the antitumour compound vernolepin is reported. The transformation of ring A of santonin into a hemiacetal δ-lactone was achieved in eleven steps. The spectroscopic characteristics of the synthetic product obtained in this way revealed that the proposed structure for the natural product should be revised.

Stereoselective Synthesis of 8,12-Furanoeudesmanes from Santonin. Absolute Stereochemistry of Natural Furanoeudesma-1,3-diene and Tubipofurane.

Ketobutenolide 3, easily obtained from santonin (1), has been transformed into two natural furanoeudesmanes 4 and 5, isolated from Commiphora molmol and Tubipora musica, respectively. trans- And cis-decalin systems were obtained by stereoselective reduction of the C(4)-C(5) double bond in 3 in the following way: hydrogenation of 3 over Pd/C followed by acidic treatment gave the cis isomer 10 as the major product; selective hydrogenation of the C(1)-C(2) double bond with the Wilkinson's catalyst followed by reduction with NaTeH yielded mainly the trans isomer 9. Compounds 9 and 10 were transformed into 4 and 5 in parallel sequences. Optical rotation and CD measurements of the synthetic produ…

ChemInform Abstract: Stereoselective Synthesis of 8,12-Furanoeudesmanes from Santonin. Absolute Stereochemistry of Natural Furanoeudesma-1,3-diene and Tubipofurane.

Ketobutenolide 3, easily obtained from santonin (1), has been transformed into two natural furanoeudesmanes 4 and 5, isolated from Commiphora molmol and Tubipora musica, respectively. trans- And cis-decalin systems were obtained by stereoselective reduction of the C4−C5 double bond in 3 in the following way:  hydrogenation of 3 over Pd/C followed by acidic treatment gave the cis isomer 10 as the major product; selective hydrogenation of the C1-C2 double bond with the Wilkinson’s catalyst followed by reduction with NaTeH yielded mainly the trans isomer 9. Compounds 9 and 10 were transformed into 4 and 5 in parallel sequences. Optical rotation and CD measurements of the synthetic products rev…

ChemInform Abstract: Synthesis of Elemane Bis-lactones from Santonin - Synthesis of the Reported Structure of seco-Isoerivanin Pseudo Acid and Formal Synthesis of (+)-8-Deoxyvernolepin.

The synthesis of the reported structure for seco-isoerivanin pseudo acid (1) and of an elemane bis-lactone 5 from santonin (4) through a common vinylic precursor 12 is described. Compound 5 is a known intermediate in a previous synthesis of the antitumor compound (+)-8-deoxyvernolepin (3). The vinyl group of 12 underwent a regio- and diastereoselective anti addition of an external electrophile and an intramolecular condensation to yield either the selenolactone 13 or the hydroxylactone 17. The lactones 13 and 17 served as key intermediates in the total synthesis of 1 and 5 respectively. A revision of the structure of seco-isoerivanin pseudo acid to the C-10 epimer is suggested on the basis …

ChemInform Abstract: Ring-Opening Aminolysis of Sesquiterpene Lactones: An Easy Entry to Bioactive Sesquiterpene Derivatives. Synthesis of (+)-β-Cyperone and (-)-Eudesma-3,5-diene from Santonin.

Abstract Santonin ( 1 ) and other sesquiterpene lactones ( 2–3 ) react with pyrrolidine and other cyclic secondary amines to afford γ-hydroxyamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated amides 4a-4c, 5a-5c and 6 . Starting from amides 5a-5c a series of bioactive compounds against Locusta migratoria have been prepared, differing in the oxidation states of the C-3 and C-12 carbon atoms. Starting from amides 5a and 6 two conjugated diene eudesmanes (+)-β-cyperone ( 15 ) and (−)eudesma-3,5-diene ( 19 ) have been prepared involving an elaboration of the amide group of the side chain of the eudesmane skeleton.

ChemInform Abstract: Synthesis of (+)-Isoalantolactone and (+)-Isoalloalantolactone from (-) -Santonin.

Abstract This paper reports on the chemical conversion of (−)-santonin into (+)-isoalantolactone and (+)-isoalloalantolactone involving functionality transfer from C 6 to C 8 , refunctionalization of the ring A and the formation of the α-methylene-8 β,12-olide moiety.

Combined spectroscopic and theoretical analysis of the binding of a water-soluble perylene diimide to DNA/RNA polynucleotides and G-quadruplexes.

We present here a combined spectroscopic and theoretical analysis of the binding of N,N’-bis(2-(1-piperazino)ethyl)-3,4,9,10-perylenetetracarboxylic acid diimide dichloride (PZPERY) to different biosubstrates. Absorbance titrations and circular dichroism experiments, melting studies and isothermal calorimetry (ITC) titrations reveal a picture where the binding to natural double-stranded DNA is very different from that to double and triple-stranded RNAs (poly(A)∙poly(U) and poly(U)∙poly(A)⁎poly(U)). As confirmed also by the structural and energetic details clarified by density functional theory (DFT) calculations, intercalation occurs for DNA, with a process driven by the combination of aggr…

Experimental and theoretical characterization of the strong effects on DNA stability caused by half-sandwich Ru(II) and Ir(III) bearing thiabendazole complexes

Abstract: The synthesis and characterization of two half-sandwich complexes of Ru(II) and Ir(III) with thiabendazole as ancillary ligand and their DNA binding ability were investigated using experimental and computational methods. 1H NMR and acid–base studies have shown that aquo-complexes are the reactive species. Kinetic studies show that both complexes bind covalently to DNA through the metal site and non covalently through the ancillary ligand. Thermal stability studies, viscosity, circular dichroism measurements and quantum chemical calculations have shown that the covalent binding causes breaking of the H-bonding between base pairs, bringing about DNA denaturation and compaction. Addi…

Stereoselective synthesis of 7,11-guaien-8,12-olides from santonin. Synthesis of podoandin and (+)-zedolactone A.

Photochemical rearrangement of hydroxy ester 2, easily obtained from santonin (1), afforded butenolide 4, a good starting material for the synthesis of 7,11-guaien-8,12-olides. Compound 4 has been transformed into compound 10, which has been used for the synthesis of podoandin (5) and (+)-zedolactone A (ent-6). Regioselective elimination of the acetyl group on C10 afforded directly podoandin (5). For the synthesis of ent-6, a hydroxyl group has been regio- and stereoselectively introduced at the 4alpha-position through the 3alpha,4alpha-epoxide 15. The basic hydrolysis of the 10-acetyl group in compound 18 took place with concomitant intramolecular conjugated addition of the alkoxide to the…

ChemInform Abstract: Synthesis of Plagiochiline N from Santonin.

This article reports the transformation of O-acetylisophotosantonin, obtained by photochemical rearrangement of santonin, into plagiochiline N, an ent-2,3-secoaromadendrane isolated from Plagiochila ovalifolia. The synthesis was carried out in a sequence involving as the key steps (a) the substitution of the lactone moiety by a gem-dimethylcyclopropane ring through a synthetic intermediate having a C(6)-C(7) double bond and (b) the ozonolysis of the C(2)-C(3) bond followed by cyclization to the dihydropyran ring characteristic of plagiochiline N. Spectroscopic data of the synthetic product fully coincided with the reported data for the natural product.

Synthesis of elemane bis-lactones structurally related to vernolepin

Abstract The chemical transformation of santonin into an elemane bis -lactone structurally related to the antitumour compound vernolepin is reported. The transformation of ring A of santonin into a hemiacetal δ-lactone was achieved in eleven steps. The spectroscopic characteristics of the synthetic product obtained in this way revealed that the proposed structure for the natural product should be revised.

Silver Atomic Quantum Clusters of Three Atoms for Cancer Therapy: Targeting Chromatin Compaction to Increase the Therapeutic Index of Chemotherapy

Nanomaterials with very low atomicity deserve consideration as potential pharmacological agents owing to their very small size and to their properties that can be precisely tuned with minor modifications to their size. Here, it is shown that silver clusters of three atoms (Ag3 -AQCs)-developed by an ad hoc method-augment chromatin accessibility. This effect only occurs during DNA replication. Coadministration of Ag3 -AQCs increases the cytotoxic effect of DNA-acting drugs on human lung carcinoma cells. In mice with orthotopic lung tumors, the coadministration of Ag3 -AQCs increases the amount of cisplatin (CDDP) bound to the tumor DNA by fivefold without modifying CDDP levels in normal tiss…

Synthesis of various natural 8,12-elemanolides from artemisin

Abstract This paper describes the chemical transformations of artemisin into various natural 8,12-elemanolides.

ChemInform Abstract: Synthesis of (+)-Pechueloic Acid and (+)-Aciphyllene. Revision of the Structure of (+)-Aciphyllene.

Abstract 1α H ,7α H ,10α H -Guaia-4,11-dien-3-one and its 1β H ,10β H diastereomer, easily obtained from (+)-dihydrocarvone, are good starting materials for the synthesis of natural guaiane derivatives. Allylic oxidation of the 1α H ,10α H isomer gave as main product its 13-hydroxy derivative and a small amount of (+)-7β-hydroxy-1α H ,10α H -guaia-4,11-dien-3-one, whereas the 1β H ,10β H diastereomer afforded selectively the (−)-7α-hydroxy-1β H ,10β H enantiomer in excellent yield. From the 13-hydroxy derivative (+)-pechueloic acid and (+)-methyl pechueloate were synthesized. Deoxygenation at C 3 of the 1β H ,10β H guaiadienone afforded a guaiadiene with the reported structure for aciphylle…

Synthesis of two natural 8-oxo-β-cyperone derivatives from (−)-santonin.

Abstract This paper reports on the chemical transformations of (−)-santonin into (+)-8-oxo-β-cyperone and (+)-12-hydroxy-8-oxo-β-cyperone involving 8-oxo group introduction and elaboration of the side chain.

Regio- and stereoselective oxyfunctionalization at C-1 and C-5 in sesquiterpene guaianolides

Abstract The regio- and stereoselective functionalization at C-1 and C-5 positions in a guaiane skeleton by allylic hydroxylation are described. The stereochemistry of the resulting compounds are identical to those of the majority of natural 1- and 5-hydroxy-guaianolides.

Ag2 and Ag3 clusters: synthesis, characterization, and interaction with DNA.

Subnanometric samples, containing exclusively Ag2 and Ag3 clusters, were synthesized for the first time by kinetic control using an electrochemical technique without the use of surfactants or capping agents. By combination of thermodynamic and kinetic measurements and theoretical calculations, we show herein that Ag3 clusters interact with DNA through intercalation, inducing significant structural distortion to the DNA. The lifetime of Ag3 clusters in the intercalated position is two to three orders of magnitude longer than for classical organic intercalators, such as ethidium bromide or proflavine. Fil: Buceta, David. Universidad de Santiago de Compostela; España Fil: Busto, Natalia. Unive…

Fishing for G-quadruplexes in solution with a perylene diimide derivative labeled with biotins

A new fluorescent, non‐cytotoxic perylene diimide derivative with two biotins at the peri position, PDI2B, has been synthesized. This molecule is able to interact selectively with G‐quadruplexes with scarce or no affinity towards single‐ or double‐stranded DNA. These features have made it possible to design a simple, effective, safe, cheap, and selective method for fishing G‐quadruplex structures in solution by use of PDI2B and streptavidin coated magnetic beads. The new cyclic method reported leads to the recovery of more than 80 % of G‐quadruplex structures from solution, even in the presence of an excess of single‐stranded or duplex DNA as competitors. Moreover, PDI2B is a G4 ligand that…

6-Prenyloxy-7-methoxycoumarin, a coumarin-hemiterpene ether from Carduus tenuiflorus

Abstract From the acetone extract of Carduus tenuiflorus , a new coumarin-hemiterpene ether was isolated, which was identified as 6-(3,3-dimethylallyloxy)-7-methoxycoumarin. The synthesis of this coumarin and that of its positional isomer 7-(3,3-dimethylallyloxy)-6-methoxycoumarin were carried out from esculetin. Two other coumarins, three lignans and three flavonoids were also isolated.

Synthetic studies toward natural furanosesquiterpenoids from santonin. Synthesis of (+)-1,2-dihydrotubipofuran

Abstract Santonin (1) was converted into (+)-1,2-dihydrotubipofuran (13) via a synthetic pathway involving a very easy preparation of 7,11-ene-8,12-olide and 8,12-furan moieties and A-ring elaboration on the eudesmane framework.

ChemInform Abstract: Ultrasound-Assisted Reductive Cleavage of Eudesmane and Guaiane γ-Enonelactones. Synthesis of 1α,7α,10αH-Guaian-4,11-dien-3-one and Hydrocolorenone from Santonin.

Abstract Ultrasound enhances the rate of reductive cleavage of the C6–oxygen bond of sesquiterpene enonelactones. trans-Eudesmanolides 1c–1g, cis-eudesmanolides 2a–2c, and trans-guaianolides 4a–4d react with Zn in acetic acid–H2O under sonochemical conditions to afford the corresponding sesquiterpene acids 3a–3g and 5a–5d, respectively in good yields. Starting from 5d two natural guaianes 1α,7α,10αH-guaian-4,11-dien-3-one (6) and hydrocolorenone (7) have been prepared in good yields through a straightforward sequence.

Total syntheses of (+)-temisin, (+)-melitensin and related elemanolides from (-)-artemisin

Abstract (+)-Temisin, (+)-melitensin, and related sesquiterpene lactones have been synthesized from (-)-artemisin.

ChemInform Abstract: Synthesis of Two Natural 8-Oxo-β-cyperone Derivatives from (-)- Santonin.

Abstract This paper reports on the chemical transformations of (−)-santonin into (+)-8-oxo-β-cyperone and (+)-12-hydroxy-8-oxo-β-cyperone involving 8-oxo group introduction and elaboration of the side chain.

New Sesquiterpene Lactones and Other Constituents fromCentaurea paui

Aerial parts of Centaurea paui afforded, in addition to several known sesquiterpene lactones, the two new elemanolides 2–4, the new elemane derivative 5 as well as the five new heliangolides 14–18. Their structures were elucidated by spectroscopic methods, especially high-field NMR spectroscopy. The structure of the heliangolide 12 previously isolated from this plant, has been confirmed by X-ray diffraction.

ChemInform Abstract: Transformation of Artemisin Into Artapshin and 8α-Hydroxy-11β,13-Dihydrobalchanin.

Abstract Partial syntheses of the sesquiterpene lactones artapshin ( 1 ) and 8α-hydroxy-11β, 13-dihydrobalchanin ( 2 ) from artemisin ( 3 ) are described.

Rearrangement of 4,5-epoxy-9-trimethylsilyldecalines. Application to the synthesis of the natural eremophilane (-)-aristolochene.

Several 4,5-epoxy-9-trimethylsilyl-eudesmanes and 15-nor-eudesmanes, having different relative stereochemistry and substitution at the oxirane ring, have been prepared starting from (-)-carvone and subjected to acid-promoted rearrangement. The presence of the silicon at C9 favors two different main reaction pathways involving C14-methyl or C1-methylene migration through the stabilization of a C10 carbocation intermediate. Selective 1,2-migration of the bridgehead methyl group takes place with trisubstituted beta-epoxide and tetrasubstituted alpha-epoxide, yielding 4-hydroxy-eremophilane and 15-nor-eremophilane compounds, while the trisubstituted alpha-epoxide suffers successive rearrangemen…

Eudesmane and elemane derivatives from Onopordon acaulon

Abstract From the methanol extract of Onopordon acaulon 11 sesquiterpenes were isolated. Two elemane and three eudesmane derivatives are described for the first time.

Strong Influence of the Ancillary Ligand over the Photodynamic Anticancer Properties of Neutral Biscyclometalated IrIII Complexes Bearing 2-Benzoazole-Phenolates

In this paper, the synthesis, comprehensive characterization and biological and photocatalytic properties of two series of neutral IrIII biscyclometalated complexes of general formula [Ir(C^N)2(N^O)], where the N^O ligands are 2‐(benzimidazolyl)phenolate‐N,O (L1, series a) and 2‐(benzothiazolyl)phenolate‐N,O (L2, series b), and the C^N ligands are 2‐(phenyl)pyridinate or its derivatives, are described,. Complexes of types a and b exhibit dissimilar photophysical and biological properties. In vitro cytotoxicity tests conclusively prove that derivatives of series a are harmless in the dark against SW480 cancer cells (colon adenocarcinoma), but express enhanced cytotoxicity versus the same cel…

Sesquiterpene lactones, flavonoids and coumarins from Centaurea collina

Abstract The isolation and characterization of two coumarins, five flavonoids and four sesquiterpene lactones from the aerial parts of Centaurea collina are reported. The 13 C NMR data are included.

Reductive cleavage of 2,2,2-trichloroethyl esters with sodium telluride

Abstract Carboxylic acids are regenerated from their 2,2,2-trichloroethyl esters by treatment with sodium telluride in dimethylformamide in smooth conditions and with good yields. The reaction conditions are compatible with other functional and protective groups such as methyl ester, acetate or tert-butyldimethylsilyl ethers.

DNA-binding of nickel(II), copper(II) and zinc(II) complexes: structure-affinity relationships

Abstract Nickel(II), copper(II) and zinc(II) complexes with the same ligands normally display analogous coordination geometry and binding mode toward DNA. However, although qualitatively alike in structure and properties, different DNA-binding ability has often been observed. This review surveys the most recent examples of binding of the three metal ions complexed with monodentate and chelating bidentate to tetradentate ligands to DNA. An attempt has also been made to rationalize the observed trend in the values of the intrinsic DNA-binding constant, Kb, in terms of structural and chemical features.

Synthesis of (+)-Isoalantolactone and (+)-Isoalloalantolactone from (−)-Santonin

Abstract This paper reports on the chemical conversion of (−)-santonin into (+)-isoalantolactone and (+)-isoalloalantolactone involving functionality transfer from C 6 to C 8 , refunctionalization of the ring A and the formation of the α-methylene-8 β,12-olide moiety.

Transformation of artemisin into artapshin and 8α-hydroxy-11β,13-dihydrobalchanin

Abstract Partial syntheses of the sesquiterpene lactones artapshin ( 1 ) and 8α-hydroxy-11β, 13-dihydrobalchanin ( 2 ) from artemisin ( 3 ) are described.

Nanomedicine: Silver Atomic Quantum Clusters of Three Atoms for Cancer Therapy: Targeting Chromatin Compaction to Increase the Therapeutic Index of Chemotherapy (Adv. Mater. 33/2018)

Kinetic evidence for interaction of TMPyP4 with two different G-quadruplex conformations of human telomeric DNA

Background: Stabilization of G-quadruplex helices by small ligands has attracted growing attention because they inhibit the activity of the enzyme telomerase, which is overexpressed in> 80% cancer cells. TMPyP4, one of the most studied G-quadruplex ligands, is used as a model to show that the ligands can exhibit different binding features with different conformations of a human telomeric specific sequence. Methods: UV–Vis, FRET melting Assay, Isothermal Titration Calorimetry, Time-resolved Fluorescence lifetime, T-Jump and Molecular Dynamics. Results: TMPyP4 yields two different complexes with two Tel22 telomeric conformations in the presence of Na+ or K+. T-Jump kinetic experiments show th…

Synthesis of plagiochiline N from santonin.

This article reports the transformation of O-acetylisophotosantonin, obtained by photochemical rearrangement of santonin, into plagiochiline N, an ent-2,3-secoaromadendrane isolated from Plagiochila ovalifolia. The synthesis was carried out in a sequence involving as the key steps (a) the substitution of the lactone moiety by a gem-dimethylcyclopropane ring through a synthetic intermediate having a C(6)-C(7) double bond and (b) the ozonolysis of the C(2)-C(3) bond followed by cyclization to the dihydropyran ring characteristic of plagiochiline N. Spectroscopic data of the synthetic product fully coincided with the reported data for the natural product.

Synthesis of Sesquiterpenes via silicon-guided rearrangement of epoxydecalins

A survey of the rearrangement of methyldecalins via C-5 carbocation intermediates, with special attention to the silicon-guided rearrangement of epoxydecalins is provided. A TMS group properly positioned on either C-1 or C-9 promotes the acidic rearrangement of 10-methyl-4,5-epoxydecalins and 10-methyl-5,6-epoxydecalins with exclusive migration toward C-5 of the methyl or methylene groups linked directly to C-10. The application of this biomimetic approach to the synthesis of a number of spirocyclic and eremophilane sesquiterpenes is reported.

Synthesis of all 7αH-guaia-4,11-dien-3-one diastereomers from (+)-dihydrocarvone

Abstract All four 7α H -guaia-4,11-dien-3-one diastereomers have been synthesized from the common intermediate 1α H ,10α-acetoxy-7α H -guaia-4,11-dien-3-one obtained from (+)-dihydrocarvone. The spectral features of the four diasteromers have been correlated and the structure and absolute configuration of 1β H ,10β H ,7α H -guaia-4,11-dien-3-one isolated from Pleocarphus revolutus has been confirmed.

Oxidation of N-Acyl-pyrrolidones to Imides with CrO3·3,5-dimethylpyrazole

Abstract N -Acyl-pyrrolidones are easily obtained by treatment of N -acyl-pyrrolidines with CrO 3 ·3,5-dimethylpyrazole complex (CrO 3 ·3,5-DMP) at room temperature.

ChemInform Abstract: Reductive Cleavage of 2,2,2-Trichloroethyl Esters with Sodium Telluride.

Abstract Carboxylic acids are regenerated from their 2,2,2-trichloroethyl esters by treatment with sodium telluride in dimethylformamide in smooth conditions and with good yields. The reaction conditions are compatible with other functional and protective groups such as methyl ester, acetate or tert-butyldimethylsilyl ethers.

Synthesis of (+)-pechueloic acid and (+)-aciphyllene. Revision of the structure of (+)-aciphyllene

Abstract 1α H ,7α H ,10α H -Guaia-4,11-dien-3-one and its 1β H ,10β H diastereomer, easily obtained from (+)-dihydrocarvone, are good starting materials for the synthesis of natural guaiane derivatives. Allylic oxidation of the 1α H ,10α H isomer gave as main product its 13-hydroxy derivative and a small amount of (+)-7β-hydroxy-1α H ,10α H -guaia-4,11-dien-3-one, whereas the 1β H ,10β H diastereomer afforded selectively the (−)-7α-hydroxy-1β H ,10β H enantiomer in excellent yield. From the 13-hydroxy derivative (+)-pechueloic acid and (+)-methyl pechueloate were synthesized. Deoxygenation at C 3 of the 1β H ,10β H guaiadienone afforded a guaiadiene with the reported structure for aciphylle…

A non-catalyzed ring-opening aminolysis reaction of sesquiterpene lactones

Abstract Santonin (1) and other sesquiterpene lactones (6–10) react cleanly with pyrrolidine at room temperature to afford γ-hydroxyalkylamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated alkylamides.

Synthesis of 9-oxyfunctionalized eudesmanes from artemisin

Abstract Artemisin ( 1 ) was transformed into two natural sesquiterpenoids 2 and 3 in a sequence which involves functionality transfer from C 8 to C 9 and further elaboration of the A ring and the lactone moiety.

Disolución, precipitación y cristalización. Separaciones sólido-líquido: decantación y filtración

Elaboración de material digital y recursos en la red para el tercer curso de la titulación de Química y nuevos grados. En este vídeo se muestran las técnicas básicas de laboratorio para separar una mezcla de tres compuestos en función de su solubilidad en agua: arena, sulfato de cobre pentahidrato y ácido benzoico.

CCDC 1857871: Experimental Crystal Structure Determination

Related Article: Marta Martínez-Alonso, Natalia Busto, Larry Danilo Aguirre, Leticia Berlanga, M. Carmen Carrión, José V. Cuevas, Ana M. Rodríguez, Arancha Carbayo, Blanca R. Manzano, Enrique Ortí, Félix A. Jalón, Begoña García, Gustavo Espino|2018|Chem.-Eur.J.|24|17523|doi:10.1002/chem.201803784

Cálculos estequiométricos: reacción entre carbonato de calcio y ácido clorhídrico.

Vídeo perteneciente al Proyecto de Innovación Educativa ''Elaboración de material digital y recursos en la red para asignaturas de grados impartidas por el Departamento de Ingeniería Química y la Facultad de Químicas(IDIQ)'' en el que se muestran las técnicas básicas de laboratorio para la cuantificación de la cantidad de dióxido de carbono desprendido al mezclar carbonato cálcico con ácido clorhídrico. Producció: Servei de Formació Permanent i Innovació Educativa (http://www.uv.es/sfpie)